Previous studies have shown that stromal cells of rat bone marrow can produce bonelike mineralized tissue in vitro in the presence of dexamethasone, one of the synthetic glucocorticoids. To determine whether other steroid hormones have the same effect, we did the following experiment. Bone marrow cells of femora from male Wistar rats (5 weeks old) were cultured in the medium supplemented with various concentrations of the steroid hormones. Predonisolone, triamcinolone, hydrocortisone and aldosterone also induced mineralized tissue and the induction ability of these hormones corresponds with glucocorticoid effect, not mineralocorticoid effect. Hydrocortisone induces mineralized tissue at a physiological concentration (100nM). We conclude that mineralized tissue formation in this culture system in the presence of a glucocorticoid is physiological and this system is useful for bone research.Various changes in bone tissue with aging have been reported and our working hypothesis is that dec
… Morerease of the number of osteoprogenitors in bone tissue is one of the backgrounds of bone aging. We cultured bone marrow cells from rats of different ages at different cell concentration and then measured mineralized tissue. The results indicates the dramatic decrease of the number of osteoprogenitors in bone marrow tissue with aging.Since recent in vivo studies have shown that administration of prostaglandin E2 (PGE2) increases bone mass, we investigated the effects of PGE2 on mineralized tissue formation in bone marrow cell culture system. Effects of PGE2 on mineralized tissue formation in this culture system depend on concentration and time. High concentration of PGE2 (1muM) completely inhibited the mineralized tissue formation. However, 100-10nM of PGE2 stimulated it. Interestingly, pulse addition of PGE2, from 3 to 5 days, cell growth stage in this culture system, greatly increased the amount of mineralized tissue and the number of mineralized nodules. The results indicates that anabolic effect of PGE2 in bone tissue is partly due to the increase of osteoprogenitors. Less